The diesel engine has been used for commercial, industrial, agricultural and other heavy duty applications for well over 100 years. The fundamental diesel engine cycle promotes high part-power fuel efficiency and has therefore become the engine type of choice for commercial and agricultural purposes. Although the diesel engine has outstanding efficiency and long term durability, environmental issues have increased in significance with substantial increases in urban populations throughout the world. Nowhere is this force more evident than in the United States, beginning with the Environmental Protection Agency (EPA) established over 30 years ago. During the ensuing years, the EPA has proposed and adopted ever increasing emissions limits for on-highway vehicles. The application of these standards has now been applied to off-road vehicles such as tractors, combines and other vehicles not normally driven on public highways including power generation systems. The EPA has adopted successive tiers of emissions requirements and the most recent is Tier IV. This requirement necessitates a diesel particulate filter (DPF) along with a requirement for regeneration of the filter to remove particulate matter accumulated on the filter.
A number of systems have been proposed to regenerate filters, relying on the fact that diesel particulate matter combusts when local temperatures are above 600° C. These systems may include engine management, resistive heating coils, microwave generation, and a fuel burner to increase the exhaust temperature. Another system is hydrocarbon injection in the form of atomized fuel upstream of a catalytic oxidizer to increase the exhaust temperature around the filter. One of the problems with such a system is that the fuel nozzle and lines leading to the nozzle are subjected to high ambient temperatures reaching into the region where the hydrocarbon fuel tends to coke and form deposits in the fuel nozzle and associated supply passages.
The solution to this problem for heavy duty on-highway vehicles is to blow out the line with compressed air from the standard air brake system supply tank, usually at around 100 pounds per square inch (psi). While the system is feasible for highway diesel propulsion systems it is not available for off-highway agricultural equipment which typically does not use compressed air as a power source for an air brake system.
Thus, there exists a need in the art for a regeneration system that employs a purging process with compressed air from a source other than a dedicated pump and reservoir for compressed air.